Old thread but…
I’ve had F5s for gosh almost 20 years now but these are not current model and no integrated subs. They are in a larger size L shaped room. They do very well as is and I have never used a sub. I also have smaller model with 8” driver and no sub ever with those either. If you match the Ohm to room size as advised and power them adequately adding a sub done right can’t hurt but certainly optional.
I heard the powered F5s at a show a few years back. @bondmanp got it right. One thing to consider is if you would prefer the subs on board as with the current F5s or simply add separate sub or subs of your own choosing. Pros and cons either way. Hope this helps.